On the phone from his home in Norfolk, Chris Carter sounds perturbed. "You're not planning on doing that, are you?" he asks. There's something pleasing about the note of shock in his voice. After all, Carter is a former member of Throbbing Gristle, a band that so shocked the late Tory MP Nicholas Fairbairn that he described them as "the wreckers of civilisation".

That was 26 years ago. Today, Carter's tone has hints of paternal anxiety, as befits a man whose website features photographs of him cuddling his son. "I hope you're all right," he says. "I hope your ears don't bleed or your brain turn to mush." I appreciate Carter's concern, but it is not quite the response I was hoping for when I informed him of my plan to listen to a new box set of live Throbbing Gristle CDs - 24 of them, each lasting an hour - in one go.

In its day, the racket Throbbing Gristle made was unlike anything heard before. It was allied to grim visions of Nazi death camps, serial killers, urban decay and imminent apocalypse. Today, their sound and iconography have been assimilated into the mainstream. Rock stars call themselves Marilyn Manson, arenas are filled by bands making a punishing noise and record shops devote acres to "industrial music", a genre whose title Throbbing Gristle coined. Do the originators still have the power to shock and horrify? What better way to find out than a concentrated, unadulterated blast of their blare?

In addition, the length of the box set, released by Mute, seems provocative. There is the implicit suggestion that no one with their mental capabilities fully intact would want to listen to Throbbing Gristle for 24 hours. For weeks, I have been discussing doing just that with a smug bravado. Now, as I talk to Carter, the smug bravado is wearing off. "When we first put it out [on cassette in 1980], someone listened to it on a Walkman for 24 hours," he confides. "He was a wreck."

He is not the only person to express reservations. An apocalyptic scenario will apparently erupt in my sitting room if a single note reaches my partner's ears. Luckily, headphones are recommended by the box set's sleeve notes. Further down the page, I notice a troubling caveat: "Industrial Records and Throbbing Gristle will not be held responsible in any way whatsoever for any physical, mental or structural damage either inflicted or incurred by the owner of this collection or any third parties."

At 8am on Saturday, I plug in my headphones. The voice of Throbbing Gristle vocalist Genesis P-Orridge crackles into life, on stage at the ICA in October 1976. Any last vestiges of smug bravado are evaporated by his opening speech, which may rank as the least auspicious introduction to a concert in history. "It's called Music from the Death Factory," he announces. "It's basically about the post-breakdown of civilisation." Then a churning, grey din begins, in which individual instruments are indistinguishable. When individual instruments do become distinguishable, you wish they hadn't: Genesis P-Orridge had a way with a violin that can still make your teeth hurt.

It soon becomes apparent that Throbbing Gristle's secret weapon was not their homemade instruments (including a primitive sampler), nor P-Orridge's unique bass guitar technique, which one mortified critic compared unfavourably to that of a gorilla with its hands severed. It was P-Orridge's voice, a grating, Mancunian-accented whine that somehow manages to sound out of tune even when there is no apparent tune to be out of. His lyrics are no picnic either: gas chambers, murdering pregnant women and, on one occasion, a lengthy and disheartening improvisation about the Queen and Prince Philip having sex.

If I am disheartened, that's nothing compared with the way Throbbing Gristle's early audiences felt. As P-Orridge launches into a song called We Hate You, they sound like they are fighting for the exits. Sometimes they give up and start fighting with the band. One CD features a fan seizing the microphone and remonstrating with the audience. His argument consists of screaming "You're a bunch of fucking wankers!" at the baying crowd. This causes them to bay even louder.

Worried that if I just sit around my flat listening to Throbbing Gristle all day, I might start baying myself, I venture outside. This proves to be the biggest error of judgment I have made since embarking on the project in the first place. It's difficult to know exactly what would be the ideal activity to engage in while Throbbing Gristle provide the soundtrack. But I can reveal that shopping in central London is not among them. A journey by Tube is even more like a descent into some netherworld of the damned than usual. The heaving crowds of Oxford Street, nerve- jangling at the best of times, are rendered nightmarish.

I stand it until about 4pm: less than halfway through my 24-hour marathon. Aware I am regarding my fellow shoppers with bulging eyes and am in danger of developing a twitch, I rip off my headphones. I am unprepared for what happens next. My ears are assaulted by the most appalling noise I have heard all day: children screaming, couples arguing, teenage girls bawling at each other, buskers playing tinny carols and, underpinning it all, Cliff Richard's Mistletoe and Wine. I replace my headphones. Throbbing Gristle are treating the patrons of Highbury Roundhouse to a song called Hit by a Rock. "Blood and brains in the marmalade!" wails Genesis P-Orridge, as ever grasping for a tune that may not exist. It is a distinct improvement.

Bolstered by this nirvana-like revelation, the next few hours pass happily. When I get home, my partner is watching Popstars: The Rivals. For the second time, I feel curiously thankful for Throbbing Gristle. That's not to say that the rest of the night is easy. At one stage, I doze off and wake to the sound of P-Orridge singing the old music-hall number Hello, Hello, Who's Your Lady Friend? to a backing that sounds like two cybermen kicking a dustbin around an alley. I become worried about the rumoured presence of subsonic and ultrasonic frequencies, designed to make listeners throw up, pass out or void their bowels. It would be a shame to come this far, then end up crapping myself.

But it doesn't happen. After 24 hours, I'm exhausted, but have rendered myself impervious to the sound of Throbbing Gristle: the volume surges, the screeches of feedback, even P-Orridge's voice.

Over the past 24 hours, their music has sounded awe-inspiring, hopelessly amateurish, packed with ideas and just rubbish, but anyone who argues that its power to unsettle has been diminished by time is wrong. Nevertheless, if you listen to it too much, you become immune. Perhaps my experience mirrored Throbbing Gristle's own. "It just got a bit too safe, a bit too formulaic - that's why we stopped," Carter says. With that thought in mind, I clamber thankfully into bed.